Abstract: A crystal reference (100) comprises a crystal element (102) integrally housed with a memory device (108), and is coupled to the memory device through an anti-resonant network (110). The network is designed such that it presents a high impedance at the natural frequency of the crystal element. Temperature performance information for the particular crystal element is stored in the memory device, and is accessed via terminal (112) using a single wire interface protocol.

Abstract: A frequency synthesizer circuit, having first and second modes of operation, comprises a voltage-controlled oscillator (VCO) (64), a low-pass filter (74), a phase-locked loop (PLL) (67), an analog-to-digital converter (50), a digital-to-analog converter (56), a controller (48), and a VCO input switch. During the first mode, the VCO input switch couples the control input of the VCO to a control signal produced by the PLL, and the analog-to-digital converter measures the control signal and provides it to the controller which stores the control voltage measured by the analog-to-digital converter. During the second mode, the VCO input switch couples the control input of the VCO to the digital-to-analog converter which applies the stored control to the control input of the VCO.