US 11,894,810 B2
Low noise amplifier circuit for a thermal varying resistance
Mattia Fausto Moretti, Monza (IT); Paolo Pulici, Lainate (IT); and Alessio Facen, Macerata (IT)
Assigned to STMICROELECTRONICS S.R.L., Agrate Brianza (IT)
Filed by STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed on Sep. 26, 2022, as Appl. No. 17/952,574.
Application 17/952,574 is a continuation of application No. 17/172,676, filed on Feb. 10, 2021, granted, now 11,489,496.
Application 17/172,676 is a continuation of application No. 16/392,009, filed on Apr. 23, 2019, granted, now 10,965,254, issued on Mar. 30, 2021.
Claims priority of application No. 102018000006016 (IT), filed on Jun. 4, 2018; and application No. 102018000006020 (IT), filed on Jun. 4, 2018.
Prior Publication US 2023/0009311 A1, Jan. 12, 2023
Int. Cl. H03F 1/26 (2006.01); H03F 3/45 (2006.01)
CPC H03F 1/26 (2013.01) [H03F 3/45192 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A circuit for sensing and controlling a fly height of a tip in a hard disk drive comprising the circuit, an input of the circuit coupled to a sense resistor at a first sense terminal and a second sense terminal, the circuit comprising:
a first amplifier circuit comprising a first transistor, a first load resistor, a first capacitor, a first control circuit, and a first current generator, the first control circuit configured to selectively apply a negative bias voltage supply to the first transistor; and
a second amplifier circuit comprising a second transistor, a second load resistor, a second capacitor, and a second current generator,
wherein each of the first amplifier circuit and the second amplifier circuit is configured to:
receive input signals from the sense resistor, and
amplify the input signals in accordance with a variation in resistance at the sense resistor.