Telefonaktiebolaget Lm Ericsson (Publ)

Emensa Technology Ltd. Co.

Infineon Technologies Wireless Solutions Sweden Ab

Jiren Yuan

Cheng Chen

Yijun Zhou

The present invention introduces a sub-converter stage used in a pipelined analog-to-digital converter. The sub-converter stage comprises an amplifier with a gain A, a sub analog-to-digital converter with comparators and a digital unit, a first capacitor with capacitance C, a second capacitor with capacitance C&#x2212;&#x394;C, and customized reference signal V, where If the gain A of the amplifier is adjustable, the sub-converter stage needs an error detector to detect the difference between the output of the amplifier and reference signal Vand adjust the gain A of the amplifier. The present invention also introduces a pipelined analog-to-digital converter employing the sub-converter stage. In the pipelined analog-to-digital converter and the sub-converter stage presented by this invention, the error generated by the finite gain of amplifier and the error generated by the capacitance mismatch have the same size but opposite sign, ending that the two errors can compensate each other. As a result, the sub-converter stage achieves an error-free conversion and the two errors are calibrated.

Pipelined analog-to-digital converter and sub-converter stage

A charge sampling circuit, has a control signal generator for controlling an analog input signal to the charge sampling circuit to be integrated by an integrator during a sampling phase responsive to a sampling signal from the control signal generator. The current of the analog input signal is integrated to an integrated charge for producing a proportional voltage or current sample at a signal output at the end of the sampling phase.

Versatile charge sampling circuits

The present invention relates to an analog-to-digital converter, especially to a pipelined analog-to-digital converter with calibration of capacitor mismatch and finite gain error. Comparing with the conventional pipelined analog-to-digital converter, the new analog-to-digital converter comprises more circuit blocks including an extra sub-converter stage, a control clock generator and an error detector, resulting in that each sub-converter stage has two operation modes: normal conversion mode and calibration mode. All of the sub-converter stages share one error detector which amplifies the output of the sub-converter stage in calibration mode. Furthermore, to store the output of the error detector, a memory is used in each sub-converter stage for controlling the gain of amplifier in order to make the error generated by the finite gain of amplifier and the error generated by the capacitance mismatch have the same size but opposite sign. As a result, the two errors can compensate each other to achieve an error-free conversion stage.

Pipelined analog-to-digital converter with calibration of capacitor mismatch and finite gain error

Various embodiments of a direct digital amplitude modulator (DDAM) for modulating radio frequency (RF) or intermediate frequency (IF) or baseband signal with the invented interpolation technique are disclosed. The interpolation technique greatly reduces the amplitudes of alias signals without using an analog filter. The embodiments therefore are significant for various communication transmitters to achieve simple structure, good linearity and high power efficiency.

Direct digital amplitude modulator

A charge sampling circuit, having a control signal generator for controlling an analog input signal to the charge sampling circuit to be integrated by an integrator during a sampling phase responsive to a sampling signal from the control signal generator is presented. The current of the analog input signal is integrated to an integrated charge for producing one of a proportional voltage and current sample at a signal output at the end of the sampling phase.

The demand on very high resolution A/D converter can be eliminated by using the invented floating-point A/D converter when the resolution is merely used for covering the signal dynamic range rather than the quantization accuracy. This can be achieved by producing m amplified analog signals with amplifications 2,where k&equals;constant and i&equals;1, 2, . . . m. The largest linearly amplified signal will be selected by a logic circuit (after sampling) and converted into an n-bit digital data code by an A/D converter. In the same time, the logic circuit produces an m-bit logic flag code. The n-bit data code (u), the m-bit logic flag code (v) and the constant k are combined to form a final digital output uv,with n&plus;(m&minus;1)k bits. In this way, the resolution and dynamic range can be designed independently. Unlike the know logarithmic amplifier solution, the floating-point A/D converter give a linear digital code output directly without using any look-up table. For large and small signals, the effective resolutions are kept constant (or quasi-constant to be accurate). It is also very useful to work with a small input range imposed by a low power supply voltage since its virtual input range is much larger than the actual one. As an A/D converter, its accuracy distribution along the signal amplitude is more rational, an advantage similar to that of a floating-point number representation.

Growing community of inventors

Lund, Sweden

Jiren Yuan