US 12,355,409 B2
Variable gain amplifier with cross-coupled common mode reduction
Maik Fuhs, Kierspe (DE)
Assigned to Kandou Labs SA, Lausanne (CH)
Filed by Kandou Labs SA, Lausanne (CH)
Filed on Mar. 24, 2022, as Appl. No. 17/702,884.
Prior Publication US 2023/0308064 A1, Sep. 28, 2023
Int. Cl. H03F 3/45 (2006.01); H03D 7/14 (2006.01)
CPC H03F 3/45475 (2013.01) [H03D 7/1458 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method comprising:
receiving a differential input voltage signal at an input of a variable gain amplifier (VGA), and responsively generating an amplified differential output voltage signal on a pair of output nodes by driving a pair of load impedances connected to the pair of output nodes with an amplifier current according to the differential input voltage signal;
receiving a gain control signal at the VGA;
enabling, responsive to a determination that the gain control signal is associated with a predetermined range of gain settings, a cross-coupled differential pair connected in parallel to the pair of load impedances, the cross-coupled differential pair having drain inputs and cross-coupled gate inputs connected to the pair of output nodes to supplement a gain of the amplified differential voltage output voltage signal; and
reducing a common mode voltage of the amplified differential output voltage signal by lowering the amplifier current driving the pair of load impedances via a bias control signal, the amplifier current lowered responsive to detecting the supplemented gain of the amplified differential output voltage signal.