摘要:
System and method for increasing the frequency tuning range of a RF/microwave LC oscillator. A preferred embodiment comprises a voltage controlled oscillator (VCO) configured to generate an output signal at a frequency that is dependent upon a magnitude of an input voltage level and an effective inductance of an inductive load and a variable inductor coupled to the VCO. The variable inductor comprises a primary inductor coupled to the VCO to produce a magnetic field based upon a current flowing through the primary inductor and a secondary inductor magnetically coupled to the primary inductor, the secondary inductor to affect the magnitude of the effective inductance of the primary inductor.
摘要:
System and method for increasing the frequency tuning range of a RF/microwave LC oscillator. A preferred embodiment comprises a voltage controlled oscillator (VCO) configured to generate an output signal at a frequency that is dependent upon a magnitude of an input voltage level and an effective inductance of an inductive load and a variable inductor coupled to the VCO. The variable inductor comprises a primary inductor coupled to the VCO to produce a magnetic field based upon a current flowing through the primary inductor and a secondary inductor magnetically coupled to the primary inductor, the secondary inductor to affect the magnitude of the effective inductance of the primary inductor.
摘要:
A novel method and apparatus for a negative contributive offset compensation mechanism for a transmit buffer adapted to compensate for the positive offset generated by higher order sigma-delta modulators used to amplitude modulate the transmit buffer. The positive outputs from the sigma-delta modulator are processed differently than the negative outputs. The inverters associated with the negative outputs in the sigma-delta modulator are removed and the clock signal used to drive the transistors corresponding to the negative outputs is negated or shifted 180 degrees from the clock used to drive the transistors corresponding to the positive outputs. A non-inverted version of the clock is used with the positive outputs and an inverse clock is used with the negative outputs. Use of the inverse clock causes a negative contributive offset to be generated that is added on the second half cycle of each clock. The result is an offset compensated RF output signal having zero offset.
摘要:
A transmitter (10) based on a frequency synthesizer includes an LC tank (12) of a digitally controlled oscillator (DCO) with various arrays of capacitors. The LC tank 12 is divided into two major groups that reflect two general operational modes: acquisition and tracking. The first group (process/voltage/temperature and acquisition) approximately sets the desired center frequency of oscillation initially, while the second group (integer and fractional tracking) precisely controls the oscillating frequency during the actual operation. For highly accurate outputs, dynamic element matching (DEM) is used in the integer tracking controller to reduce non-linearities caused by non-uniform capacitor values. Also, a preferred range of the integer tracking capacitor array may be used for modulation after the selected channel has been acquired. A digital sigma-delta modulator circuit (50) drives a capacitor array (14d) in response to the fractional bits of the error word. On mode switches, the accumulated error is recalculated to a phase restart value to prevent perturbations.
摘要:
A novel method and apparatus for a negative contributive offset compensation mechanism for a transmit buffer adapted to compensate for the positive offset generated by higher order sigma-delta modulators used to amplitude modulate the transmit buffer. The positive outputs from the sigma-delta modulator are processed differently than the negative outputs. The inverters associated with the negative outputs in the sigma-delta modulator are removed and the clock signal used to drive the transistors corresponding to the negative outputs is negated or shifted 180 degrees from the clock used to drive the transistors corresponding to the positive outputs. A non-inverted version of the clock is used with the positive outputs and an inverse clock is used with the negative outputs. Use of the inverse clock causes a negative contributive offset to be generated that is added on the second half cycle of each clock. The result is an offset compensated RF output signal having zero offset.
摘要:
An on-chip test mechanism for transceiver power amplifier and oscillator frequency for use with the transmitter portion of an integrated RF transceiver. The RF output from the power amplifier in the transmitter is input to a built-in dedicated analog comparator having a configurable threshold. The threshold is adjusted to a predetermined level at which crossings start to occur at the comparator output. The comparator outputs pulses only if the power amplifier output is above a minimum configurable level. The comparator output is input to a frequency divider whose frequency output is tested by a low cost external tester to determine the actual RF frequency thereby confirming generation of the correct oscillator frequency and that the amplitude of the signal at the output of the power amplifier is sufficiently high for the configurable threshold level to be exceeded, thereby determining the compliance of the output power with its defined specifications.
摘要:
A low noise amplifier (LNA) operates over multiple frequency bands while occupying less silicon area than known LNA implementations. The LNA includes output matching that can be tuned by an adjustable inductor together with a tunable capacitor bank.
摘要:
The application of a non-zero voltage offset to rotating capacitors 1111 and 1112 permit the use of a single positive voltage supply. However, the precharging of the rotating capacitors 1111 and 1112 is power inefficient. A power efficient and low-noise precharging operation is realized through the sharing of the charge on a feedback capacitor 1075 and 1080 that is significantly larger than the rotating capacitors 1111. Once a precharging operation is complete, the charge on the feedback capacitor 1075 and 1080 is refreshed from its residual charge level (rather than zero charge level) to a desired charge level.
摘要:
A novel apparatus for a low noise, high isolation, all digital transmit buffer gain control mechanism. The gain control scheme is presented in the context of an all digital direct digital-to-RF amplitude converter (DRAC), which efficiently combines the traditional transmit chain functions of upconversion, I and Q combining, D/A conversion, filtering, buffering and RF output amplitude control into a single circuit. The transmit buffer is constructed as an array of NMOS switches. The control logic for each NMOS switch comprises a pass-gate type AND gate whose inputs are the phase modulated output of an all digital PLL and the amplitude control word from a digital control block. Power control is accomplished by recognizing the impairments suffered by a pseudo class E pre-power amplifier (PPA) when implemented in a CMOS process. Firstly, the NMOS switches of the array have significant on resistance and thus can only draw a limited current from the an RF choke when the input waveform is high. The significant on resistance of the NMOS switches is exploited in the DRAC circuit to introduce power control of the transmitted waveform and permits a fully digital method of controlling the RF output power.
摘要:
System and method for increasing the frequency tuning range of a RF/microwave LC oscillator. A preferred embodiment comprises a voltage controlled oscillator (VCO) configured to generate an output signal at a frequency that is dependent upon a magnitude of an input voltage level and an effective inductance of an inductive load and a variable inductor coupled to the VCO. The variable inductor comprises a primary inductor coupled to the VCO to produce a magnetic field based upon a current flowing through the primary inductor and a secondary inductor magnetically coupled to the primary inductor, the secondary inductor to affect the magnitude of the effective inductance of the primary inductor.