US 11,689,157 B2
Low power relaxation oscillator circuit
Ricardo Pureza Coimbra, Campinas (BR); and Luis Enrique Del Castillo, Sao Paulo (BR)
Assigned to NXP B.V., Eindhoven (NL)
Filed by NXP B.V., Eindhoven (NL)
Filed on Sep. 7, 2021, as Appl. No. 17/468,191.
Prior Publication US 2023/0071036 A1, Mar. 9, 2023
Int. Cl. H03B 5/20 (2006.01); H03K 3/037 (2006.01); H03K 5/24 (2006.01)
CPC H03B 5/20 (2013.01) [H03K 3/037 (2013.01); H03K 5/24 (2013.01)] 16 Claims
OG exemplary drawing
 
1. An apparatus comprising:
an oscillator for generating an oscillating signal, the oscillator comprising:
a first comparator for comparing voltages at first and second inputs, respectively;
a first capacitor coupled to the first input of the first comparator;
a first circuit configured for charging the first capacitor to a first voltage, wherein the first voltage is related to a propagation delay of the first comparator and varies with the propagation delay of the first comparator;
a second capacitor;
a third capacitor;
a current source for charging the second capacitor or the third capacitor with a substantially constant current;
a first switch for coupling the first capacitor in series with the second capacitor as the second capacitor is being charged by the current source; and
a second switch for coupling the first capacitor in series with the third capacitor as the third capacitor is being charged by the current source.