US 12,241,920 B2
Frequency monitoring circuitry with voltage conversion
Arunvenkatesh Alagappan, Cupertino, CA (US); Soheil Golara, San Jose, CA (US); and Seyedeh Sedigheh Hashemi, Los Altos, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Nov. 14, 2022, as Appl. No. 17/986,612.
Claims priority of provisional application 63/408,782, filed on Sep. 21, 2022.
Prior Publication US 2024/0110959 A1, Apr. 4, 2024
Int. Cl. G01R 23/02 (2006.01); G01R 23/09 (2006.01); G01R 23/10 (2006.01); H03K 21/02 (2006.01)
CPC G01R 23/02 (2013.01) [G01R 23/09 (2013.01); G01R 23/10 (2013.01); H03K 21/02 (2013.01)] 20 Claims
OG exemplary drawing
 
1. Frequency monitoring circuitry comprising:
a comparator having a first comparator input and a second comparator input;
a capacitor coupled to the first comparator input;
a resistor selectively coupled to the second comparator input; and
a current source configured to provide a reference current to the capacitor during a first time period and to provide the reference current to the resistor during a second time period different than the first time period.