• Pre-trimmed Blackmer® Voltage Controlled Amplifier (VCA)
• RMS-Level Detector
• Wide supply voltage range: 4.5V ~ 16V
• Low supply current: 3.7 mA typ. (5V)
• Four opamps
• One low noise opamp (< 5 nV/√Hz)
• On board PTAT reference
• Wide dynamic range: 120 dB as compander
• Small QSOP28 & QFN24 surface mount packages

Datasheet Download

Datasheet Download
4320 Datasheet (335 kB)
Low-voltage Low-power Dynamics Processor


• Companding noise reduction systems
— Wireless microphones
— Wireless instrument packs
— Wireless in-ear monitors

• Battery-operated dynamics processors
— Compressors
— Limiters
— AGCs
— De-essers


The THAT4320 is a single-chip Analog Engine optimized for low-voltage, low-power operation in a small QSOP package. Incorporating a high-performance Blackmer® voltage- controlled amplifier (VCA), RMS-level sensor, and four opamps, the surface mount part is aimed at battery-operated audio applications such as wireless microphones, wireless instruments and in-ear monitors.

Key Specifications(see4320 datasheetfor complete specifications)




Power supply voltage

4.5 to 16


Supply current





Dynamic Range (as compander)



Gain Range

-100 to +40


Total Harmonic Distortion



Control Constant
(both positive & negative- sense control available)

± 6.0


Output Noise

0 dB gain



RMS Detector

Averaging Method

Root Mean Squared (RMS)


Output Scaling



Dynamic Range




> 20


Crest Factor

1 dB reading error



Input Offset Voltage ±1 ~ ±1.5 mV
Input Bias Current 200 ~ 500 nA
Gain-Bandwidth Product 7.3 ~ 13 MHz
Slew Rate 3.2 ~ 4 V/µs
Input Voltage Noise OA1
OA3 & 4



Order Number

Pricing (1000)

Min Order Quantity



28 Pin QSOP




Request Samples

28 Pin QSOP Tape & Reel


Contact us


24 Pin QFN 4320N24-U $6.33 73
24 Pin QFN Tape & Reel 4320N24-UR Contact us 2000
4320 Demo Board   4320-DEMO-A $150 1
All 4320 parts are RoHS compliant. Minimum Order Quantity (MOQ) is one tube or one reel. Parts must be ordered in multiples of the MOQ. Samples are available for qualified applicants. Pricing is subject to change.
ICs designated -UR are available on tape and reel for a modest increase in price and require an extended lead time. Please contact our sales department for pricing and current lead time.
Design Notes(as PDF files)

Design Note 00A
Basic Compressor/Limiter Design (113k) (formerly Application Note 100A)

Design Note 01A
The Mathematics of Log-Based Dynamic Processors (64k) (formerly Application Note 101A)

Design Note 02
Digital Gain Control with Analog VCAs (106k) (formerly Application Note 102)

Design Note 03
Signal Limiter for Power Amplifiers (95k) (formerly Application Note 103)

Design Note 04
Improving Loudspeaker Signal Handling Capability (217k) (formerly Application Note 104)

Design Note 05
A Low Parts Count, Two-Slope Compressor (78k) (Application Note 105)

Design Note 100
A Fully Adjustable Noise Gate (69k)

Design Note 101
Peak Detection with the THAT4301 (37k)

Design Note 102
Adjustable Ducker using the THAT 4301 (76k)

Design Note 107/111
A Simple Effective Soft-Knee Compressor / Limiter (81k)

Design Note 108
Single Chip Automatic Gain Control (73k)

Design Note 112
LED Bar-Graph Compression Indictor (83k)

Design Note 113
THAT4301 Gain Reduction Indicator (33k)

Design Note 114
Adaptive Attack and Release Rates using THAT RMS Detectors (48k)

Design Note 115
Fully Adjustable Compressor/Limiter (46k)

Design Note 116
Techniques for Stereo Volume Control (126k)

Design Note 117
Input Limited for ADCs (120k)

Design Note 118
High Performance Stereo AGC (90k)

Design Note 119
Wide Ranging dB Meter (177k)

Design Note 125
The “One Knob Squeezer” (90k)

Design Note 128
What’s a PTAT Temp. Coefficient, & Where Does It Come From? (64k)

Design Note 131
Dealing with the PTAT Coefficient (75k)

Design Note 132
Alternate Method of Indicating Compression (52k)

Related Products
Other Analog Engines
THAT 4305 Low-cost basic Analog Engine for dual supply voltages. 4305 Datasheet
THAT 4315 Low-voltage, low-power basic Analog Engine for single supply voltages. 4315 Datasheet
THAT 4316 Very low-voltage, low-power basic Analog Engine for single supply voltages. 4316 Datasheet
Voltage Controlled Amplifiers (VCAs)
THAT 2180 Series Pre-trimmed Blackmer VCAs 2180 Series Datasheet
THAT 2181 Series Trimmable Blackmer VCAs 2181 Series Datasheet
THAT 2162 Dual Blackmer VCAs 2162 Datasheet

Additional Resources

Analog Engine Selector
A side by side comparison of the features and specifications of our Analog Engine dynamic processor ICs.

4320 Compressor Demo Board– The THAT 4320 Demonstration System (US$150) allows the engineer to test the performance of a THAT4320 quickly and easily. The 4320 Demo Board is self-contained circuit board with XLR connectors for signal input and output and a 3-pin header for connection to an external regulated DC power supply (not included). See the 4320 Demo Board Datasheet for more information.

4320 Surface Mount Adapter Board
– For our integrated circuits which are only available in surface mount packages THAT Corporation offers adapter boards which allow one of these surface-mount ICs to interface to a circuit board via traditional thru-hole mounting. These adapters make it easy for a design engineer to evaluate our surface-mount products on a prototype board without having to employ SMT technology. Adapter boards are available to qualified applicants.

Harsh Environment Packaging
– TT Semiconductor repackages THAT Corporation’s IC products in ruggidized plastic for the medical, aerospace, defense, and heavy industrial marketplaces.

The History of VCAs
– THAT Blackmer® VCAs are the successors to the original dbx® line of VCAs. Their development for professional audio use has a long history, and can provide some insight into the care and feeding of these essential devices.

4320 Material Data Declaration Sheet
Material Data Declaration Sheets (MDDS) disclose the hazardous materials in our integrated circuits as required by the European RoHS directive.