Functional Overview

This chapter helps you to quickly get acquainted with the main features, the panels, and the operating modes of the HF2 Series. A product selector is provided listing the key features of the products in order to support the selection and ordering. This section is intended as overview and therefore has a coarse level of detail without containing detailed descriptions.

Features

hf2li functional diagram
Figure 1. HF2 functional diagram

The HF2 Instrument as in Figure 1 consists of 4 high-frequency analog blocks, 2 low-frequency auxiliary blocks, the internal digital processing block (light-blue), and the hardware interfaces (mostly available on the back panel of the instrument).

The signal to be measured is connected to one of the two high-frequency analog inputs where it is amplified to a defined range, filtered, and digitized at very high speed. The resulting samples are fed into the digital signal processing block for demodulation by means of up to 8 dual-phase demodulators. The demodulators output samples flow into the embedded RISC processor for further processing or to be sent to the host computer. The samples are also sent to the auxiliary outputs in order to be available on the front panel of the HF2 Instrument.

The numerical oscillators generate sine and cosine signal pairs that are used for the demodulation of the input samples and also for the generation of the high-frequency output signals. For this purpose, the Output Mixers generate a weighted sum of the generator outputs to generate the multi-frequency signal that can be used a stimulation signal. The 2 high-frequency output stages provide analog to digital conversion, signal scaling (range), add of an external AC or DC signal, and a synchronization signal.

Operating Modes

  • Internal reference mode

  • External reference mode

  • Auto reference mode

  • Dual-channel operation

  • Dual-harmonic mode

  • Multi-harmonic mode

  • Arbitrary frequency mode

High-frequency Analog Inputs

  • 2 low-noise high-frequency inputs

  • Differential & single-ended operation (A, -B, A-B)

  • Variable input range

  • Variable input impedance

  • AC/DC coupling

High-frequency Analog Outputs

  • 2 low-noise high-frequency outputs

  • Large output range

  • Variable output range settings

  • 1 synchronization signal for each output

  • 1 adder signal for each output

Auxiliary Analog Input/Outputs

  • 4 auxiliary high-speed outputs

  • 2 auxiliary high-speed inputs

  • User defined signal on auxiliary output

Demodulators & Reference

  • Up to 8 dual-phase demodulators

  • Up to 8 programmable numerical oscillators

  • Programmable demodulators filters

  • Very-high resolution internal reference

  • 64-bit resolution demodulator outputs

Measurement Tools

  • Spectroscope

  • Numerical

  • Oscilloscope

  • Frequency response analyzer

  • FFT spectrum analyzer

User-programmable Embedded Processor (Option)

  • Microblaze 32-bit RISC

  • 64 MHz operation allows implementation of real-time control loops

  • 32-bit floating-point unit

  • 64 kB internal memory (maximum program size)

  • 64 MB external memory DDR2

Other Interfaces

  • USB 2.0 high-speed 480 Mbit/s host interface

  • DIO: 32-bit digital input-output port

  • ZSync: 2 ports for inter-instrument synchronization bus (ZI proprietary)

  • ZCtrl: 2 ports for control/power bus for external pre-amplifiers (ZI proprietary)

  • Clock input connector (10 MHz)

Software Features

  • The LabOne User Interface, a powerful browser-based graphical interface

  • ziServer multi-mode multi-connection server

  • ziAPI for extended programmability in C, LabVIEW, MATLAB, and Python - programming examples included

  • Console: text interface to connect virtually any programming language

Front Panel Tour

The front panel BNC connectors and control LEDs are arranged in 5 sections as shown in Figure 2and Figure 3 and listed in Table 1. The HF2LI and HF2IS have the same connectors and connector functionality on their front and back panel.

hf2li frontpanel with letters
Figure 2. HF2LI front panel
hf2is frontpanel with letters
Figure 3. HF2IS front panel
Table 1. HF2 Series front panel description
Position Label / Name Description

A

Signal Input 1 + In

single-ended input

B

Signal Input 1 - In Diff

negative input (when not used, has to be internally shorted to ground with switch on graphical user interface)

C

Signal Input 1 Over

this LED indicates that the input signal saturates the A/D converter

D

Signal Input 2 / Ref + In

single ended input / reference input for external reference mode

E

Signal Input 2 / Ref - In Diff

negative input (when not used, has to be internally shorted to ground with switch on graphical user interface)

F

Signal Input 2 Over

this LED indicates that the input signal saturates the A/D converter

G

Signal Output 1 Add

the signal applied to the connector is added (analog add) to the output signal

H

Signal Output 1 Out

high-frequency output

I

Signal Output 1 Sync

the output signal before the output gain stage for use as synchronization or monitoring signal; the amplitude voltage calculates as ratio of the corresponding output amplitude and its range setting

J

Signal Output 1 On

this LED indicates that the signal output is turned on

K

Signal Output 2 Add

the signal applied to the connector is added (analog add) to the output signal

L

Signal Output 2 Out

high-frequency output

M

Signal Output 2 Sync

the output signal before the output gain stage for use as synchronization or monitoring signal; the amplitude voltage calculates as ratio of the corresponding output amplitude and its range setting

N

Signal Output 2 On

this LED indicates that the signal output is turned on

O

X/R 1 / Aux 1

this connector provides either the in-phase signal of the demodulator (X1), the magnitude (R1), or an auxiliary output signal Aux 1

P

Y/θ 1 / Aux 2

this connector provides either the quadrature signal of the demodulator (Y1), the phase (θ1), or an auxiliary output signal Aux 2

Q

X/R 2 / Aux 3

this connector provides either the in-phase signal of the demodulator (X2), the magnitude (R2), or an auxiliary output signal Aux 3

R

Y/θ 2 / Aux 4

this connector provides either the quadrature signal of the demodulator (Y2), the phase (θ2), or an auxiliary output signal Aux 4

S

Power

instrument mains power-on LED

Back Panel Tour

The back panel is the main interface for power, control, service and connectivity to other ZI instruments. Please refer to Figure 4 and Table 2 for the detailed description of the items.

hf2 backpanel with letters
Figure 4. HF2 Series back panel
Table 2. HF2 Series back panel description
Position Label / Name Description

A

-

ventilator (important: keep clear from obstruction)

B

Earth ground

4 mm banana jack connector for earth ground purpose, electrically connected to the chassis and the earth pin of the power inlet

C

Power inlet

power inlet with On/Off switch

D

Power system

select between 115 V and 230 V power system

E

ZCtrl 1

peripheral pre-amplifier power & control bus 1 - attention: this is not an Ethernet plug, connection to an Ethernet network might damage the instrument

F

ZCtrl 2

peripheral pre-amplifier power & control bus 2 - attention: this is not an Ethernet plug, connection to an Ethernet network might damage the instrument

G

Aux In 1

auxiliary high-sampling rate input 1

H

Aux In 2

auxiliary high-sampling rate input 2

I

DIO 0

digital input/output 0

J

DIO 1

digital input/output 1

K

DIO

digital input/output 0-31

L

Clock In

clock input (10 MHz)

M

ZSync In

inter-instrument synchronization bus input - attention: this is not an Ethernet plug, connection to an Ethernet network might damage the instrument

N

ZSync Out

inter-instrument synchronization bus output - attention: this is not an Ethernet plug, connection to an Ethernet network might damage the instrument

O

USB

host computer connection

Ordering Guide

The HF2 Series is a product line comprising an impedance spectroscope and a digital lock-in amplifier covering advanced requirements for laboratory equipment. The HF2 Series provides best-in-class performance, wide operation range, intuitive handling and excellent accuracy. The HF2IS Impedance Spectroscope is controlled with the ziControl user interface which is described in the ziControl Edition of the HF2 User Manual.

Table 3 provides an overview of the available products in the HF2 Series. Upgradeable features are options that can be purchased anytime without need to send the instrument to Zurich Instruments - the upgradeable features consist of a firmware upgrade.

Table 3. HF2 Series product codes for ordering
Product code Product name Description Upgrade in the field possible

HF2LI

HF2LI Lock-in Amplifier

base lock-in amplifier

-

HF2LI-MF

HF2LI-MF Multi-frequency

option

yes

HF2LI-PLL

HF2LI-PLL Dual Phase-locked Loop

option

yes

HF2LI-PID

HF2LI-PID Quad PID Controller

option

yes

HF2LI-MOD

HF2LI-MOD AM/FM Modulation

option

yes

-

-

-

-

HF2PLL

HF2PLL Phase-locked Loop

bundle of the HF2LI plus the HF2LI-PLL and the HF2LI-PID options

-

-

-

-

-

HF2IS

HF2IS Impedance Spectroscope

base impedance spectroscope

-

HF2IS-MF

HF2IS-MF Multi-frequency

option

yes

-

-

-

-

HF2TA

HF2TA Current Amplifier

low-noise transimpedance amplifier

yes

Table 4. Product selector
Feature HF2LI HF2LI + HF2LI-MF HF2IS HF2IS + HF2IS-MF

Internal reference mode

yes

yes

yes

yes

External reference mode

yes

yes

-

-

Auto reference mode

yes

yes

-

-

Dual-channel operation (2 independent measurement units)

yes

yes

yes

yes

Sinusoidal generators

2

2

2

2

Superposed output sinusoidals per generator

1

up to 6

up to 4

up to 8

Dual-harmonic mode

yes

yes

-

-

Multi-harmonic mode

-

yes

-

-

Arbitrary frequency mode

-

yes

yes

yes

Number of demodulators

6

6

4

8

Simultaneous freq. supported (fundamentals/harmonics)

2/4

6/-

4/-

8/-

Signal input select switch matrix

-

yes

yes

yes

Oscillator select switch matrix

-

yes

-

-

50 MHz, 210 MS/s, 0.8 μs TC

yes

yes

yes

yes

DSP technology

128 bit

128 bit

128 bit

128 bit

Dynamic reserve

120 dB

120 dB

-

-

Lock-in range

50 MHz

50 MHz

-

-

USB 2.0 480 Mbit/s

yes

yes

yes

yes

Instrument software

LabOne User Interface, ziAPI, ziServer software

LabOne User Interface, ziAPI, ziServer software

ziControl, ziAPI, ziServer software

ziControl, ziAPI, ziServer software

Frequency response analyzer

yes

yes

yes

yes

Oscilloscope

yes

yes

yes

yes

Operating Modes

Internal Reference Mode

The internal reference mode takes advantage of the internal HF generators inside the HF2 Instrument. There are 6 frequency generators in the HF2LI and up to 8 frequency generators in the HF2IS. The output of these generators are added numerically inside the instrument avoiding complicated external analog signal adders and the resulting signal is fed to the device under test. The internal reference mode is the preferred mode as the signal recovery works at its best as the generated frequency is known inside of the instrument. The signal acquisition works immediately and there is no delay lock-time.

The internal reference mode is supported with single-channel and dual-channel operation. This is possible as the HF2 Instrument includes 2 independent measurement units that are working autonomously. Each of the measurement units provides analysis for one fundamental and 2 harmonic frequencies in parallel (sometimes called dual-harmonic mode). In total, the HF2LI can measure 2 fundamental and 4 harmonic frequencies, while the HF2IS can measure 4 frequencies. The number of frequencies increases with the multi-frequency options.

The demodulator samples are available in analog format on the auxiliary outputs of the HF2 Instrument and digitally on the connected computer transferred over the USB interface. The auxiliary outputs generate an analog signal after a linear digital to analog conversion at high sample rate. There are 2 pairs of analog signals allowing to output any 2 of the demodulation sample streams. All demodulator streams are available on the computer and can be further analyzed or stored in the local drives.

hf2 internal refmode single
Figure 5. HF2 internal reference mode / single-channel
hf2 internal refmode dual
Figure 6. HF2 internal reference mode / dual-channel

External Reference Mode

The external reference mode uses external reference sources to recover the signal of interest inside the HF2 Instrument. In this mode, the internal frequency generators are not used to stimulate the DUT. As the signal reference is an arbitrary periodic signal, a certain amount of time is required for the HF2LI to lock on the reference and to be able to recover the signal of interest reliably. This lock time depends on several parameters, but most important on the level and phase noise of the reference.

The external reference mode is supported with single-channel and dual-channel operation. This is possible as the HF2 Instruments includes 2 independent measurement units that are working autonomously. In single-channel mode, the reference can be fed into the Input 2/Ref connector on the front panel. This alternative provides an unmatched capability to use references with small amplitudes as they can be amplified by the signal path of Input 2. In dual-channel operation, the external TTL references are fed into the HF2 by means of the DIO0 and DIO1 connectors on the back panel.

hf2 external refmode single
Figure 7. HF2 external reference mode / single-channel
hf2 external refmode dual
Figure 8. HF2 external reference mode / dual-channel

Auto Reference Mode

The auto reference mode makes use of the internal PLLs to recover the reference frequency directly from the signal coming from the DUT. In this mode, the internal frequency generators are not used to stimulate the DUT. As the reference is inherently contained in the sampled signal, a dedicated PLL is able to lock on the frequency and to recover the reference and the signal of interest. This process is suited for signals with enough amplitude and signal-to-noise ratio. Further the reference recovery requires a certain amount of time that depends on several parameters like the level and the phase noise of the measured signal.

The auto reference mode is supported with single-channel and dual-channel operation. This is possible as the HF2 Instrument includes 2 independent measurement units that are working autonomously. In dual-channel mode it is sufficient to connect the signals captures at the DUTs to the Input 1 and Input 2 connectors of the HF2 Instrument. The HF2 Series support both single-ended and differential input signals ideal for fixed and floating ground applications.

hf2 auto refmode dual
Figure 9. HF2 auto reference mode / dual-channel

Multi-frequency Operation

The multi-frequency operation is the powerful extension provided by the HF2 Series increasing the number of frequencies that can be analyzed in parallel. Moreover, the multi-frequency considerably expands the multiplexing options the user has with respect of input channels and demodulator clocks. Please note that the HF2IS-MF is different than the HF2LI-MF (see Table 4) as different features and different number of demodulators are activated.

For the HF2LI the multi-harmonic mode and the arbitrary frequency mode are distinguished. In multi-harmonic mode it is possible to analyze a signal at the fundamental frequency and at 5 harmonics at the same time, and the arbitrary frequency mode is the extension to analyze a signal of interest at 6 completely independent frequencies.

For the HF2IS only the arbitrary frequency mode is relevant.

hf2 multi harmonic mode
Figure 10. HF2 multi-harmonic mode
hf2 arbitrary frequency mode
Figure 11. HF2 arbitrary frequency mode