Tensorcom, Inc.

Nantworks, LLC

KhongMeng Tham

Zaw Soe

Ricky Lap Kei Cheung

Huainan Ma

Local oscillator (LO) leakage and Image are common and undesirable effects in typical transmitters. Typically, fairly complex hardware and algorithms are used to calibrate and reduce these impairments. A single transistor that draws essentially no dc current and occupies a very small area detects the LO leakage and Image signals. The single transistor operating as a square-law device is used to mix the signals at the input and output ports of a power amplifier. The mixed signal generated by the single transistor enables the simultaneous calibration of the LO leakage and Image Rejection.

Method and apparatus to detect lo leakage and image rejection using a single transistor

This invention eliminates the need for 'capacitor coupling' or 'transformer coupling,' and the associated undesirable parasitic capacitance and inductance associated with these coupling techniques when designing high frequency (&#x2dc;60 GHz) circuits. At this frequency, the distance between two adjacent stages needs to be minimized. A resonant circuit in series with the power or ground leads is used to isolate a biasing signal from a high frequency signal. The introduction of this resonant circuit allows a first stage to be &#x201c;directly coupled&#x201d; to a next stage using a metallic trace. The &#x201c;direct coupling&#x201d; technique passes both the high frequency signal and the biasing voltage to the next stage. The &#x201c;direct coupling&#x201d; approach overcomes the large die area usage when compared to either the &#x201c;AC coupling&#x201d; or &#x201c;transformer coupling&#x201d; approach since neither capacitors nor transformers are required to transfer the high frequency signals between stages.

Direct coupled biasing circuit for high frequency applications

Method and apparatus to detect LO leakage and image rejection using a single transistor

LO leakage and Image are common and undesirable effects in typical transmitters. Typically, thirty complex hardware and algorithms are used to calibrate and reduce these two impairments. A single transistor that draws essentially no de current and occupies a very small area, is used to detect the LO leakage and Image Rejection signals. The single transistor operating as a square law device, is used to mix the signals at the input and output ports of the power amplifier (PA). The mixed signal generated by the single transistor enables the simultaneous calibration of the LO leakage and Image Rejection.

This invention compensates for the unintentional magnetic coupling between a first and second inductor of two different closely spaced inductors separated by a conversion circuit. A cancellation circuit formed from transistors senses the magnetic coupling in the first inductor and feeds a current opposite to the induced magnetic coupling captured by the second inductor such that the coupled magnetic coupling can be compensated and allows the first and second inductors to behave independently with regards to the coupled magnetic coupling between the first and second inductors. This allows the distance between the first and second inductors to be minimized which saves silicon area. In addition, the performance is improved since the overall capacitance in both circuits can be decreased. This cancellation technique to reduce the magnetic coupling between two closed placed inductively loaded circuits allows the design of a more compact and faster performing circuit.

Method and apparatus of cancelling inductor coupling

A large gain is used to start up the oscillation of the crystal quickly. Once the oscillation starts, the amplitude is detected. A control circuit determines based on the measured amplitude to disable a low resistance path in the controlled switch array to reduce the applied gain below the power dissipation specification of the crystal. Another technique introduces a mixed-signal controlled power supply multi-path resistive array which tailors the maximum current to the crystal. A successive approximation register converts the amplitude into several partitions and enables/disables one of several power routing paths to the inverter of the oscillator. This allows a better match between the crystal selected by the customer and the on-chip drive circuitry to power up the oscillator without stressing the crystal. The 'l/f' noise of the oscillator circuit is minimized by operating transistors in the triode region instead of the linear region.

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San Diego, CA, United States of America

KhongMeng Tham