US 12,294,840 B2
Microphone amplifying circuit design method and microphone amplifying circuit
Dong Han, Singapore (SG); and Chuationg Kee, Singapore (SG)
Assigned to AAC ACOUSTIC TECHNOLOGIES (SHENZHEN) CO., LTD., Shenzhen (CN)
Appl. No. 17/918,899
Filed by AAC ACOUSTIC TECHNOLOGIES (SHENZHEN) CO., LTD., Shenzhen (CN)
PCT Filed Apr. 21, 2022, PCT No. PCT/CN2022/088162
§ 371(c)(1), (2) Date Oct. 13, 2022,
PCT Pub. No. WO2023/184625, PCT Pub. Date Oct. 5, 2023.
Claims priority of application No. 202210353358.7 (CN), filed on Apr. 1, 2022.
Prior Publication US 2025/0024199 A1, Jan. 16, 2025
Int. Cl. H04R 3/00 (2006.01); H03F 3/187 (2006.01)
CPC H04R 3/002 (2013.01) [H03F 3/187 (2013.01); H03F 2200/03 (2013.01); H03F 2200/21 (2013.01); H03F 2200/267 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A microphone amplifying circuit design method, applied to a microphone and an amplifying circuit, the amplifying circuit including an amplifier, a bias resistor connecting to an input of the amplifier by which the amplifier is connected to a bias voltage, an input end connecting to the input of the amplifier and an output end connecting to the amplifier; the method including steps of: providing a layer of underlying metal set between a substrate of an integrated circuit and a welding plate;
wherein the welding plate, the underlying metal and the substrate are insulated from each other, a first parasitic capacitor is formed between the welding plate and
the underlying metal, and a second parasitic capacitor is formed between the underlying metal and the substrate;
seeking a circuit point circuit point in the amplifying circuit, and making the circuit point satisfy the following conditions which are that:
a. the circuit point and the input end are in a same phase;
b. a voltage gain of the circuit point and the input end is greater than or equal to 0.8; 20
c. the circuit point is in a signal path from the input end to the output end;
connecting the underlying metal to the circuit point, and connecting the welding plate to the input end;
welding the microphone to the welding plate of the integrated circuit to connect the microphone and act as a microphone capacitor;
wherein one end of the microphone capacitor is connected to a high voltage bias voltage, and an other end of the microphone capacitor is connected to the input end; one end of the first parasitic capacitor is connected to the input end, and an other end of the first parasitic capacitor is connected to the output end;
the second parasitic capacitor is connected to the output end, and an other end of the second parasitic capacitor is grounded.