Functional Overview

This chapter provides the overview of the features offered by the GHFLI Lock-in Amplifier. The first section contains the description of the functional diagram, and the hardware and software feature list. The following section details the front panel and the back panel of the measurement instrument. The last section provides product selection and ordering support.

Features

The GHFLI Lock-in Amplifier consists of several internal units that process digital data (light blue color) and several interface units processing analog signals (dark blue color). The front panel is depicted on the left-hand side and the back panel is depicted on the right-hand side. The arrows between the panels and the interface units indicate selected physical connections and the data flow.

The orange blocks are optional units that can be either ordered at purchase or upgraded later. The GHFLI Lock-in Amplifier has 2 physical channels each with its own signal input and output, auxiliary input and digital inputs and outputs. The ordering guide details the currently available upgrade options.

ghfli functional diagram
Figure 1. GHFLI instrument functional diagram

The signal to be measured is usually connected to one of the two GHFLI signal inputs where it is amplified to a defined range and digitized at very high speed. The resulting samples are fed into the digital signal processor that contains 8 dual-phase demodulators. The results of the demodulation are fed into a digital interface to be transferred to the host computer through the LAN or USB interface, and can also be routed to the auxiliary outputs on the front panel of the GHFLI. Two low-distortion signal outputs provide the signal generator functionality.

The numerical oscillators generate sine and cosine pairs that are used for the demodulation of the input signal and also for the generation of the GHFLI output signals. For this purpose, when the GHFLI-MF Multi-Frequency option is present, the Output Adder can generate a linear combination of the oscillator outputs to generate a multi-frequency output signal.

Hardware trigger and reference signals are used for various purposes inside the instrument, such as triggering demodulation and oscilloscope data acquisition, to acquire or generate an external reference signal, or triggering other equipment.

Lock-in Operating Modes

  • Internal reference mode

  • External reference mode (coming later in 2023)

  • Dual-lock-in operation (two independent lock-in amplifiers in the same box)

  • Triple-harmonic mode (simultaneous measurement at three harmonic frequencies)

  • Arbitrary frequency mode (with GHF-MF option, simultaneous measurement at up to eight arbitrary frequencies)

Signal Inputs

  • 2 low-noise GHF Inputs, DC - 1.8 GHz frequency range

  • Variable input range, selectable from 10 mV to 1 V peak (50Ω)

  • Selectable AC/DC coupling

Signal Outputs

  • 2 low-noise GHF Outputs, DC - 1.8 GHz frequency range

  • Variable output range, selectable from 10 mV to 0.5 V peak (into 50Ω)

Demodulators & Reference

  • Up to 8 dual-phase demodulators

  • Up to 8 programmable numerical oscillators

  • Up to 2 external reference signals (coming later in 2023)

  • Up to 4 input and up to 4 output trigger signals

  • Individually programmable demodulator filters

  • 128-bit internal processing

  • 64-bit resolution demodulator sample

  • 48-bit internal reference resolution

Auxiliary Input and Outputs

  • 4 high-speed auxiliary outputs for user-defined signals, 25 MHz bandwidth, 14 bit

  • 4 high-precision auxiliary outputs for user-defined signals, 200 kHz bandwidth, 18 bit

  • 2 auxiliary inputs, general purpose

High-speed Connectivity

  • SMA connectors on front and back panel for triggers, signals and external clock

  • USB 3.0 high-speed host interface

  • LAN/Ethernet 1 Gbit/s controller interface

  • DIO: 32-bit digital input-output port

  • Clock input/output connectors (10/100 MHz)

Extensive Time and Frequency Domain Analysis Tools

  • Numeric tool

  • Plotter

  • Oscilloscope

  • Sweeper and Frequency response analyzer

  • FFT spectrum analyzer

  • Data Acquisition tool

Software Features

  • Web-based, high-speed LabOne® user interface with multi-instrument control

  • Data server with multi-client support

  • API for Python and MATLAB®

Front Panel Tour

The front panel SMA and BNC connectors and control LEDs are arranged as shown in Figure 2 and listed in Table 1.

ghfli front panel with letters
Figure 2. GHFLI Lock-in Amplifier front panel
Table 1. GHFLI Lock-in Amplifier front panel description
Position Label / Name Description

A

Aux In

analog Auxiliary Input, max. 10 V

B

Signal Output

single-ended analog Signal Output, DC-8.5 GHz, max. 1 V peak

C

Trig Out

TTL Trigger Outputs 1 to 4

D

Trig In

TTL Trigger Inputs 1 to 4

E

Signal Input

single-ended analog Signal Input, DC-8.5 GHz, max. 1 V peak

F

High Precision

high-precision auxiliary outputs 1 to 4

G

High Speed

high-speed auxiliary outputs 1 to 4

H

Aux In Over

this red LED indicates that the input signal saturates the A/D converter and therefore the input range must be increased or the signal must be attenuated

I

Signal Output ON

this blue LED indicates that the signal output is actively driven by the instrument

J

Signal Input Over

this red LED indicates that the input signal saturates the A/D converter and therefore the input range must be increased or the signal must be attenuated

K

multicolor LEDs
off

Instrument off or uninitialized

blink

all LEDs blink for 5 seconds → indicator used by the Identify Device functionality

Busy

unused

Ext. Clock
off

10/100 MHz External Clock Signal not present/detected

blue

10/100 MHz External Clock Signal is present and locked on to

yellow

10/100 MHz External Clock Signal present, but not locked on to

red

10/100 MHz External Clock Signal present, but lock failed

ZSync

unused

Status
off

Instrument off or uninitialized

blue

Instrument is initialized and has no warnings or errors

yellow

Instrument has warnings

red

Instrument has errors

L

on off
Soft power button

Power button with incorporated status LED

off

Instrument off and disconnected from mains power

blue

  • flashing rapidly (>1/sec): Firmware is starting

  • flashing slowly (<1/sec): Firmware ready, waiting for connection

  • constant: Instrument ready and active connection over USB or Ethernet

red

  • breathing: Instrument off but connected to mains power → safe to power off using the rear panel switch, or restart using the soft power button

  • flashing: Instrument booting up

  • constant: Fatal error occurred

Back Panel Tour

The back panel is the main interface for power, control, service and connectivity to other ZI instruments. Please refer to Figure 3 and Table 2 for the detailed description of the items.

ghfli back panel with letters
Figure 3. GHFLI Lock-in Amplifier back panel
Table 2. GHFLI Lock-in Amplifier back panel description
Position Label / Name Description

A
safety chassis gnd

Earth ground

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

B

AC 100 - 240 V

Power inlet, fuse holder, and power switch

C

MDS 1

SMA: bidirectional TTL ports for multi-device synchronization

D

MDS 2

SMA: bidirectional TTL ports for multi-device synchronization

E

USB 1

Universal Serial Bus (USB) 3.0 port for instrument control

F

LAN 1GbE

1 Gbit LAN connector for instrument control

G

DIO 32bit

32-bit digital input/output (DIO) connector

H

USB 2

Universal Serial Bus (USB) 3.0 port connector → do not use for standard operation

I

ZSync Secondary

unused

Attention: This is not an Ethernet plug, connection to an Ethernet network might damage the instrument.

J

ZSync Primary

unused

Attention: This is not an Ethernet plug, connection to an Ethernet network might damage the instrument.

K

External Clk In

external clock Input (10 MHz/100 MHz) for synchronization with other instruments

L

External Clk Out

external clock Output (10 MHz/100 MHz) for synchronization with other instruments

Ordering Guide

Table 3 provides an overview of the available GHFLI products. Upgradeable features are options that can be purchased anytime without the need to send the Instrument back to Zurich Instruments.

Table 3. GHFLI Instrument product codes for ordering
Product code Product name Description Field upgrade possible

GHFLI

GHFLI Lock-in Amplifier

base lock-in amplifier

-

GHF-MF

GHF-MF Multi-frequency

option

yes

GHF-MOD

GHF-MOD AM/FM Modulation

option

yes1,2

GHF-PID

GHF-PID Quad PID/PLL Controller

option

yes2

1 Requires GHF-MF Multi-frequency option

2 Available by end of 2023

Table 4. Product selector GHFLI
Feature GHFLI GHFLI + GHF-MF GHFLI + GHF-PID GHFLI + GHF-MF + GHF-PID

Internal reference mode

yes

yes

yes

yes

External reference mode1

yes

yes

yes

yes

Dual-channel operation (2 independent measurement units)

yes

yes

yes

yes

Signal generators

2

2

2

2

Superposed output sinusoidals per generator

1

up to 8

1

up to 8

Triple-harmonic mode

yes

yes

yes

yes

Multi-frequency mode

-

yes

-

yes

Arbitrary frequency mode

-

yes

-

yes

Number of demodulators

8

8

8

8

Simultaneous frequencies

2

8

2

8

Simultaneous numerical oscillator harmonics

4+4

-

4+4

-

External references

2

2

2

2

PID controllers

-

-

4

4

Dynamic reserve

100 dB

100 dB

100 dB

100 dB

Lock-in range

1.8 GHz

1.8 GHz

1.8 GHz

1.8 GHz

USB 3.0

yes

yes

yes

yes

LAN 1 Gbit/s

yes

yes

yes

yes

1 Available by end of 2023