摘要:
A device for implementing a method for receiving a complex baseband signal in analog form or in digital form, and providing a pulse modulated signal as a linear modulation of the complex baseband signal is disclosed. First, a complex modulated signal as a function of the complex baseband signal is generated. Second, a bandlimited exponential signal as a function of the complex modulated signal as computed with a truncated Taylor series for an exponential is generated, or a coefficient vector as a function of the complex modulated signal is generated. Finally, a pulse modulated signal as either a function of the bandlimited exponential signal or the coefficient vector is generated.
摘要:
A modulated signal source for implementing A modulated signal method of a generating a modulated signal having a radio frequency based upon a linear mixing of signals is disclosed. An in-phase pulse signal modulator of the modulated signal source provides an in-phase pulse modulated signal in response to a reception of a baseband in-phase signal and an in-phase clock signal with the in-phase clock signal and the in-phase pulse modulated signal being synchronized. A quadrature pulse signal modulator of the modulated signal source provides a quadrature pulse modulated signal in response to a reception of a baseband quadrature signal and a quadrature clock signal with the quadrature clock signal and the quadrature pulse modulated signal being synchronized. A switch signal generator of the modulated signal source generates an in-phase switch signal and a quadrature switch signal in response to a reception of the in-phase clock signal, the in-phase pulse modulated signal, the quadrature clock signal, and the quadrature pulse modulated signal. The in-phase clock signal and the in-phase switch signal are synchronized, and the quadrature clock signal and the quadrature switch signal are synchronized. A radio frequency signal generator of the modulated signal source provides one or more modulated signals having a radio frequency in response to either a reception the in-phase switch signal and the quadrature phase signal, or a reception of a switch signal as a function of the in-phase switch signal and the quadrature phase signal.
摘要:
A device for implementing a method for generating a pulse width modulated signal based upon a natural sampling technique is disclosed. First, a complex baseband signal is received by the device. Second, the device computes a first pulse edge vector and a second pulse edge vector as a function of the baseband signal. Third, the device computes a first set of natural sampling points as a function of the first pulse edge vector and computes a second set of natural sampling points as a function of the second pulse edge vector. These computations can involve one or more detections of a jump k&pgr; within the first pulse edge vector and/or the second pulse edge vector. Finally, the pulse width modulated signal is generated with pulse edges corresponding to the first set of natural sampling points and the second set of natural sampling points.
摘要:
A closed loop audio amplifier system and method of powering up/down the system without producing audible artifacts are provided. During power up, a prebias voltage is provided to each output connected to a speaker to increase the voltage to a nominal output level. High impedance switches are then driven at a 50% duty cycle. Feedback from the output is supplied to a servo, which is enabled to fine tune the output voltage. Low impedance switches are then driven at a 50% duty cycle at a quarter cycle timing. The order of the feedback loop depends on which of the high or low impedance switches are driven. The prebias voltage is then removed before audio signals to be amplified are supplied to the system. Timing of driving of the switches is programmable. To power down,. essentially the reverse sequence is provided.
摘要:
A system and method for analog-to-digital conversion using digital pulse width modulation (PWM) is disclosed. The method and system according to the disclosed invention converts an analog input signal to a digital signal in pulse code modulated (PCM) form. The disclosed invention uses a feedback circuit to perform PWM of the analog input signal. The PWM signal is then decimated to obtain the digital signal in PCM form. The system according to the disclosed invention requires lower operating frequency and dissipates lesser power than prior art systems providing the same sampling frequency and resolution. The operation at a lower frequency is achieved by obtaining two samples from every pulse of the PWM signal; the first sample being obtained from the right duty ratio, and the second sample being obtained form the left duty ratio. Further, the disclosed invention has lesser implementation complexity and higher signal-to-noise ratio than prior art.
摘要:
Method and apparatus are provided for high linearity and low noise communication signal mixing. The apparatus includes a high linearity low noise mixer having an input stage coupled to a switch stage by a series-coupled blocking capacitance and input resistance. The input stage includes a buffer with negative feedback, and the switch stage includes a transistor based switch network connected to an amplifier that has feedback resistance and shunting capacitance. The method includes AC coupling an RF signal, increasing a gain of the RF signal, reducing third-order distortion by negatively feeding-back the RF signal, blocking IM2 generated from said gain increasing step, increasing a second-order input intercept point (IIP2) by attenuating the RF signal across a resistance, and applying a local oscillator input to the RF signal.