摘要:
A very fast lock integer N PLL with hybrid digital coarse VCO tuning and VCO temperature drift compensation provides for a fully digital tuning scheme without the need for charge pumps. A PLL synthesizer (300) using such a PLL design provides for very fast lock times by using an open loop step and a closed loop step. The hybrid PLL can achieve coarse tuning within four clock cycles, while minimizing any errors caused by the VCO non-linearity. Temperature tracking and compensation is also provided. A SAR implementation (100) and an interpolation tuning implementation (200) are also described.
摘要:
The present invention discusses fractional compensation timing circuitry (15) to track a VCO output frequency, fO, and provide highly effective error cancellation in a fractional-N PLL synthesizer. This output frequency tracking is used to suppress spurious sidebands, commonly known as spurs, in both fixed-band and multi-band wireless transceiver applications which use fractional-N PLL synthesizers. Some of the critical parameters which benefit from this type of PLL include switching time, phase noise, and reference feed-through.
摘要:
A passive CMOS differential mixer circuit with a mismatch correction circuit for balancing the electrical characteristics of the two output paths. Once the output paths of the differential circuit are balanced, or matched as closely as possible, second order intermodulation product generation can be inhibited or at least reduced to acceptable levels. The mismatch correction circuit receives a digital offset signal, and generates one or more voltage signals to be selectively applied to the signal paths of the passive differential mixer circuit. The voltage signals can be adjusted back gate bias voltages applied to the bulk terminals of selected transistors to adjust their threshold voltages, or the voltage signals can be adjusted common mode voltages applied directly to a selected signal path. Since the differential mixer circuit is passive, no DC current contribution to noise is generated. The switching transistors of the mixer circuit can be maintained at minimal dimensions to reduce switching signal drive loading, resulting in lower power consumption and higher operating frequencies than if larger switching transistors were used.
摘要:
An integrated circuit (ICT) comprising a filter (50). The filter comprises an input (&ugr;in+) for receiving an input signal and an output (56) for producing an output signal having a frequency cutoff point. The filter further comprises at least one resistor network (RN1) coupled between the input and the output. The resistor network comprises a first non-switched resistance (R1.1) and a first resistance series connection connected in parallel with the first non-switched resistance. The first resistance series connection comprises a switched resistance (R1.2) connected in series with a source/drain path of a switching transistor (TRR1.2), the switching transistor having a gate for receiving a control signal. The frequency cutoff point is adjustable in response to the control signal. Additionally, the switched resistance has a first resistance and the switching transistor has an on-resistance. Further, the on-resistance is at least 20 percent of the total of the first resistance and the on-resistance.
摘要:
A power supply noise rejection circuit for functional circuits, such as a voltage controlled oscillator (VCO). The power supply noise rejection circuit includes an isolation transistor connected to a voltage supply for providing an output current and voltage substantially free of noise across the full frequency range. A current source, a diode connected reference transistor with resistance means connected between its gate and drain terminals, and a dummy circuit serially connected between the voltage supply and ground generate a bias voltage that is applied to the gate of the isolation transistor. The dummy circuit mimics the DC characteristics of the functional circuit such that the output current tracks with process and temperature variations. The isolation transistor and the reference transistor can have negative threshold voltages, and the circuit can include bleed means for drawing current from the gate of the reference transistor and isolation transistor.
摘要:
A power ramping circuit for use in the transmit path of a radio frequency (RF) circuit. The power ramping circuit includes parallel connected transistors used as logarithmic resistor attenuators for adjusting current to a mixer circuit in the transmit path. The parallel connected transistors can be sized differently, and are sequentially turned off to gradually increase the current provided to the mixer circuit. A ramp control circuit controls the parallel connected transistors in response to either an analog signal or a digital signal.
摘要:
A wireless communication device (UST), comprising an input for receiving baseband data (I, Q) in a first signal having a first frequency. The device also comprises circuitry (681, 682) for increasing the first frequency, to form a second signal having a second frequency, in response to a first frequency reference signal (IF2), and the device comprises circuitry (74) for increasing the second frequency, to form a third signal having a third frequency, in response to a second frequency reference signal (LO2). Lastly, the device comprises an antenna (ATU2) for transmitting the baseband data at a final transmission frequency selected as a band within a predetermined set of frequency bands. With reference to the preceding, the first frequency reference signal and the second frequency reference signal are variable and are selected in response to the final transmission frequency which is a particular band selected as a different band at different times and from the predetermined set of frequency bands.
摘要:
A receiver 100 is provided. The receiver 100 comprises an in-phase analog-to-digital converter 112 operable to detect a saturation condition of the in-phase analog-to-digital converter 112 and to adjust the amplitude of a in-phase signal processed by the in-phase analog-to-digital converter 112 to remove the in-phase analog-to-digital converter 112 from the saturation condition and a in-phase digital filter 114 operable to adjust a gain applied to a digital input to the in-phase digital filter 114 from the in-phase analog-to-digital converter 112, the adjustment of the gain substantially inversely proportional to the adjustment of the amplitude of the in-phase signal processed by the in-phase analog-to-digital converter 112. In an embodiment, the receiver 100 also comprises a quadrature path that is substantially similar to the in-phase path, and the in-phase path and the quadrature path comprise a direct conversion receiver. In an embodiment, the in-phase analog-to-digital converter 112 and the in-phase digital filter 114 comprise an intermediate frequency receiver.
摘要:
Programmable linear-in-dB or linear bias current source with respect to an input voltage is provided. The linear-in-dB or linear bias current may be clipped at a minimum current level, a maximum current level, or a combination thereof. Preferably, the minimum and maximum current levels are determined by the use of one or more constant current sources. The constant current sources limit the amount of voltage applied to the gates of one or more transistors, which in turn control the output current. The use of the circuit may be used to generate linear or reverse-linear current levels with respect to an input voltage. The output of the current generator may be used as an input to a power-amplifier driver, for example.
摘要:
A new family of current mode logic (CML) gates (14) which, in one embodiment includes OR/NOR and AND/NAND gates, as well as more complex logic functions. The circuit uses a complementary signal to drive the gate of a feedback transistor (19) which has the effect of pseudo differential operation. Although it uses only single-ended inputs (A, B), because of this feedback aspect, the circuit has many of the advantages of a differential circuit such as low-voltage operation, higher immunity to noise, and less sensitivity to parasitic elements.