# US 2022/0045658 A1 · Two-stage audio gain circuit based on analog-to-digital conversion and audio terminal

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- Number: US 2022/0045658 A1
- Document ID: US20220045658A1
- Status: Published application
- Kind: A1
- Application number: 17/508,686
- Filed: 2021-10-22
- Published: 2022-02-10
- Earliest claimed: 2019-04-29
- Assignees: Radiawave Technologies Co., Ltd.
- Applicants: Radiawave Technologies Co., Ltd.
- Inventors: Liuan ZHANG; Yulin TAN; Jon Sweat DUSTER; Ning ZHANG; Haigang FENG; Erkan ALPMAN
- Web page: https://patentgrep.com/patent/US20220045658A1

## CPC

- H03G 3/3005: {in amplifiers suitable for low-frequencies, e.g. audio amplifiers (H03G3/32, H03G3/34 take precedence)}
- G11B 20/10027: {adjusting the signal strength during recording or reproduction, e.g. variable gain amplifiers (optimum power control for optical discs G11B7/125)}
- H03G 3/001: {Digital control of analog signals}
- H03M 1/185: {the determination of the range being based on more than one digital output value, e.g. on a running average, a power estimation or the rate of change}
- G11B 20/10037: {A/D conversion, D/A conversion, sampling, slicing and digital quantisation or adjusting parameters thereof}
- H03G: CONTROL OF AMPLIFICATION
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)

## Abstract

Disclosed are a two-stage audio gain circuit based on analog-to-digital conversion and an audio terminal. The two-stage audio gain circuit includes a PGA configured to receive an analog audio signal and perform programmable gain amplification processing on the received analog audio signal; an ADC configured to convert the analog audio signal after the programmable gain amplification processing into a digital audio signal and output the digital audio signal; a first AGC gain unit configured to perform a first AGC processing on the digital audio signal and output a first gain adjustment value to the PGA, for the PGA to perform gain adjustment on the received analog audio signal; and a second AGC gain unit configured to perform a second AGC processing on the digital audio signal and output a second gain adjustment value to the PGA, for the PGA to perform gain adjustment on the received analog audio signal.

## Claims

### Claim 1

A two-stage audio gain circuit based on analog-to-digital conversion, comprising:
a programmable gain amplifier (PGA) configured to receive an analog audio signal and perform programmable gain amplification processing on the received analog audio signal;
an analog-to-digital converter configured to convert the analog audio signal after the programmable gain amplification processing into a digital audio signal and output the digital audio signal;
a first automatic gain control (AGC) gain unit configured to perform a first AGC processing on the digital audio signal and output a first gain adjustment value to the PGA, for the PGA to perform gain adjustment on the received analog audio signal according to the first gain adjustment value; and
a second AGC gain unit configured to perform a second AGC processing on the digital audio signal and output a second gain adjustment value to the PGA, for the PGA to perform gain adjustment on the received analog audio signal according to the second gain adjustment value.

### Claim 2 (depends on 1)

The two-stage audio gain circuit based on analog-to-digital conversion of claim 1, wherein the second AGC gain unit is further configured to convert the second gain adjustment value into a multiplier coefficient;
the two-stage audio gain circuit based on analog-to-digital conversion further comprises:
a multiplier configured to multiply the digital audio signal with the multiplier coefficient converted by the second AGC gain unit to perform digital gain adjustment.

### Claim 3 (depends on 1)

The two-stage audio gain circuit based on analog-to-digital conversion of claim 1, wherein both the first AGC gain unit and the second AGC gain unit comprise:
an envelope taking unit configured to perform absolute value processing on an audio value of the digital audio signal to take an absolution value of the audio value, and obtain an envelope curve of the digital audio signal;
a moving average unit configured to perform moving average processing on the envelope curve;
an amplitude statistics unit configured to perform statistics on an effective value of the envelope curve after the moving average processing, and output an effective statistical value; and
a gain value output unit configured to obtain and output a gain adjustment value to be adjusted according to the effective statistical value.

### Claim 4 (depends on 3)

The two-stage audio gain circuit based on analog-to-digital conversion of claim 3, wherein the gain value output unit comprises a soft AGC unit, a table look-up AGC unit and a data selector;
the soft AGC unit is configured to determine the gain adjustment value to be adjusted according to a current effective statistical value and a preset target gain value;
the table look-up AGC unit is configured to look up a preset gain adjustment value mapping table according to the current effective statistical value to determine the gain adjustment value to be adjusted; and
the data selector is configured to output the gain adjustment value determined by the soft AGC unit or output the gain adjustment value determined by the table look-up AGC unit.

### Claim 5 (depends on 3)

The two-stage audio gain circuit based on analog-to-digital conversion of claim 3, wherein the moving average unit is configured to perform moving average processing on the envelope curve according to a preset calculation formula [X(n)+X(n−1)+ . . . +X(n−N+1)]/N; X is an absolute value of the audio value of the digital audio signal, and N is any number from 1 to 128.

### Claim 6 (depends on 1)

The two-stage audio gain circuit based on analog-to-digital conversion of claim 1, wherein the PGA comprises a first PGA and a second PGA;
the first PGA is configured to perform a first gain adjustment on the received analog audio signal according to the first gain adjustment value; and
the second PGA is configured to perform a second gain adjustment on the received analog audio signal according to the second gain adjustment value.

### Claim 7 (depends on 6)

The two-stage audio gain circuit based on analog-to-digital conversion of claim 6, wherein the first gain adjustment is adjusted in a first preset range, and an adjustment accuracy of the first preset range is a first preset accuracy;
the second gain adjustment is adjusted in a second preset range, and an adjustment accuracy of the second preset range is a second preset accuracy; and
the first preset accuracy is greater than the second preset accuracy.

### Claim 8 (depends on 1)

The two-stage audio gain circuit based on analog-to-digital conversion of claim 1, further comprising a filter unit configured to perform filtering processing on the digital audio signal for which the PGA performs gain adjustment.

### Claim 9 (depends on 8)

The two-stage audio gain circuit based on analog-to-digital conversion of claim 8, wherein the filter unit comprises a cascaded integrator-comb (CIC) filter, a first half band filter (HBF) and a second HBF connected in sequence,
an input end of the CIC filter is an input end of the filter unit, and an output end of the second HBF is an output end of the filter unit.

### Claim 10 (depends on 1)

An audio terminal, comprising the two-stage audio gain circuit based on analog-to-digital conversion of claim 1.