Single-end-to-differential microphone circuit and electronic equipment

Patent metadata

Field	Value
Publication number	US-12335694-B2
Application number	US-202217918895-A
Country	US
Kind code	B2
Filing date	May 20, 2022
Priority date	Apr 19, 2022
Publication date	Jun 17, 2025
Grant date	Jun 17, 2025

Abstract

The present invention provides a single-end-to-differential microphone circuit and an electronic equipment, including: an amplifier, a microphone connected to the positive input end of the amplifier, a coupling capacitor C AC connected to the negative input end of the amplifier, a first feedback capacitor C FB1 connected to the negative output end of the amplifier, a first feedback resistor R FB1 connected in parallel with the first feedback capacitor C FB1 , a second feedback capacitor connected to the positive output end of the amplifier C FB2 , and a second feedback resistor R FB2 connected in parallel with the second feedback capacitor C FB1 . The circuit of the present invention can adopt a microphone structure with smaller capacity, and at the same time has a better system signal to noise ratio.

First claim

What is claimed is:

1. A single-end-to-differential microphone circuit, including:
an amplifier;
a microphone connected to a positive input end of the amplifier;
a coupling capacitor C AC connected to a negative input end of the amplifier;
a first feedback capacitor C FB1 connected to a negative output end of the amplifier;
a first feedback resistor R FB1 connected in parallel with the first feedback capacitor C FB1 ;
a second feedback capacitor C FB2 connected to a positive output end of the amplifier;
a second feedback resistor R FB2 connected in parallel with the second feedback capacitor C FB2 ; wherein
the microphone and an input end of the coupling capacitor C AC are connected to a bias resistor R B which enables an AC signal to be input at the positive input end and the negative input end of the amplifier at the same time;
the amplifier includes: a p-type input transistor M 1 , a p-type input transistor M 2 , a n-type input transistor M 3 , a n-type input transistor M 4 , and an output load;
source electrodes of the p-type input transistor M 1 and the p-type input transistor M 2 are connected to a bias current IB;
grid electrodes of the p-type input transistor M 1 and the p-type input transistor M 2 are respectively connected to the positive input end and the negative input end of the amplifier;
the n-type input transistor M 3 and the n-type input transistor M 4 are respectively connected to drain electrodes of the p-type input transistor M 1 and the p-type input transistor M 2 ;
grid electrodes of the n-type input transistor M 3 and the n-type input transistor M 4 are respectively connected to the positive input end and the negative input end of the amplifier; and
source electrodes of the n-type input transistor M 3 and the n-type input transistor M 4 are respectively connected to the output load.

2. The single-end-to-differential microphone circuit as described in claim 1 , wherein a capacity of the coupling capacitor C AC is at least 4 times that of the microphone.

3. The single-end-to-differential microphone circuit as described in claim 1 , wherein the output load is a load transistor M 5 and a load transistor M 6 ; grid electrodes of the load transistor M 5 and the load transistor M 6 are respectively connected to the drain electrodes of the p-type input transistor M 1 and the p-type input transistor M 2 ; drain electrodes of the load transistor M 5 and the load transistor M 6 are respectively connected to the source electrodes of the n-type input transistor M 3 and the n-type input transistor M 4 .

4. The single-end-to-differential microphone circuit as described in claim 1 , wherein, an equivalent capacity of the microphone is less than 2 pF.

5. An electronic equipment including a single-end-to-differential microphone circuit, wherein the single-end-to-differential microphone circuit includes:
an amplifier;
a microphone connected to a positive input end of the amplifier;
a coupling capacitor C AC connected to a negative input end of the amplifier;
a first feedback capacitor C FB1 connected to a negative output end of the amplifier;
a first feedback resistor R FB1 connected in parallel with the first feedback capacitor C FB1 ,
a second feedback capacitor C FB2 connected to a positive output end of the amplifier,
and a second feedback resistor R FB2 connected in parallel with the second feedback capacitor C FB2 ; and wherein
the microphone and the input end of the coupling capacitor C AC are connected to a bias resistor R B which enables the AC signal to be input at the positive input end and the negative input end of the amplifier at the same time,
the amplifier includes: a p-type input transistor M 1 , a p-type input transistor M 2 , a n-type input transistor M 3 , a n-type input transistor M 4 , and an output load;
source electrodes of the p-type input transistor M 1 and the p-type input transistor M 2 are connected to a bias current IB, and grid electrodes of the p-type input transistor M 1 and the p-type input transistor M 2 are respectively connected to the positive input end and the negative input end of the amplifier;
the n-type input transistor M 3 and the n-type input transistor M 4 are respectively connected to drain electrodes of the p-type input transistor M 1 and the p-type input transistor M 2 ;
grid electrodes of the n-type input transistor M 3 and the n-type input transistor M 4 are respectively connected to the positive input end and the negative input end of the amplifier;
source electrodes of the n-type input transistor M 3 and the n-type input transistor M 4 are respectively connected to the output load.

6. The electronic equipment as described in claim 5 , wherein, a capacitance of the coupling capacitor C AC is at least 4 times that of the microphone.

7. The electronic equipment as described in claim 5 , wherein the output load is a load transistor M 5 and a load transistor M 6 ;
grid electrodes of the load transistor M 5 and the load transistor M 6 are respectively connected to the drain electrodes of the p-type input transistor M 1 and the p-type input transistor M 2 ;
drain electrodes of the load transistor M 5 and the load transistor M 6 are respectively connected to the source electrodes of the n-type input transistor M 3 and the n-type input transistor M 4 .

8. The electronic equipment as described in claim 5 , wherein an equivalent capacitance of the microphone is less than 2 pF.

Assignees

• Aac Acoustic Tech Shenzhen Co Ltd

Inventors

• Han Dong
• Kee Chuationg

Classifications

• H03F3/45479

  characterised by the way of common mode signal rejection · CPC title

• H03F1/26 Primary

  Modifications of amplifiers to reduce influence of noise generated by amplifying elements · CPC title

• H03F2203/45526

  the FBC comprising a resistor-capacitor combination and being coupled between the LC and the IC · CPC title

• H03F3/45237

  Complementary long tailed pairs having parallel inputs and being supplied in series · CPC title

• H03F3/187

  in integrated circuits · CPC title