Abstract:
A voltage controlled oscillator of a phase locked loop circuit having digitally controlled gain compensation. The digital control circuitry provides binary logic input to the voltage controlled oscillator for a digitally controlled variable resistance circuit, a digitally controlled variable current transconductor circuit, or differential transistor pairs having mirrored circuitry for adjusting the V-I gain. The latter configuration requires the voltage controlled oscillator to incorporate a source-coupled differential pair which is driven by a low pass filter capacitor output voltage, and connected to load transistors; a current source and a current mirror for generating a tail current; individual banks of transistors to mirror the load transistor currents; a digital-to-analog converter with control lines outputted there from, the digital-to-analog converter used to increase the amount of current allowed to flow to the transconductor output, the current being digitally increased and decreased corresponding to an amount of current pulled from the current source, and mirroring the current through at least one transistor mirror circuit.
Abstract:
A voltage-controlled oscillator is provided having a semiconductor integrated circuit and a piezoelectric resonator. A variable-capacitance diode may be connected in series with the piezoelectric resonator. The variable-capacitance diode may be further mounted a land of a lead frame. The piezoelectric resonator, variable-capacitance diode and lead frame may be resin molded into a single unit. In operation, a signal may be applied to a node located between the variable-capacitance diode and the DC-cutting capacitor.
Abstract:
An injection locking oscillator (ILO) comprising a tank circuit having a digitally controlled capacitor bank, a cross-coupled differential transistor pair coupled to the tank circuit, at least one signal injection node, and at least one output node configured to provide an injection locked output signal; a digitally controlled injection-ratio circuit having an injection output coupled to the at least one signal injection node, configured to accept an input signal and to generate an adjustable injection signal applied to the at least one injection node; and, an ILO controller connected to the capacitor bank and the injection-ratio circuit configured to apply a control signal to the capacitor bank to adjust a resonant frequency of the tank circuit and to apply a control signal to the injection-ratio circuit to adjust a signal injection ratio.
Abstract:
A DCXO device comprises a crystal resonator (13), and a binary weighted switched capacitor network (14) with a switchable capacitance. A microprocessor (12) is provided for controlling the switched capacitor network to obtain a desired oscillation frequency of the DCXO device. The microprocessor receives (i) an actual oscillation frequency value (16) of the DCXO device and (ii) a desired oscillation frequency value (17), e.g. from a radio base station. The processor is further arranged to calculate a capacitance difference (ΔC 1 ) required for tuning the DCXO device from the actual oscillation frequency value to the desired oscillation frequency value based on static (C 0 ) and motional (C m ) capacitances of the crystal resonator, on the capacitance (C 1 ) of the DCXO device, and on the actual and desired oscillation frequency values, and to switch the switched capacitor network in response to the calculated capacitance difference.