Active quadrature signal generator using load having low-pass and high-pass filter characteristics
AssigneeElectronics and Telecommunications Research Institute
InventorsKwang Jin Koh, Hyun Kyu Yu
Life of this patent
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Abstract
An active quadrature signal generator produces poly-phase quadrature signals necessary in high frequency transmit and receive elements of a communication system. The quadrature signals are produced using the phase difference between a load representing a low-pass filter characteristic and a load representing a high-pass filter characteristic and the quadrature signal is then used in the differential structure to produce amplified signal having 4 quadrature phases. The device can reduce a loss characteristic of the signal and additional power consumption for compensating for it in a common poly-phase quadrature filter having only conventional resistors and capacitor.
Claims8
An active quadrature signal generator, comprising:
- a pair of different connected transistors (201,202), wherein each of two differential signals (VCO in+,VCO in−) having different relative phases are inputted into each of the input terminals of the pair of the transistors and converted to differential current signals;
- two pairs of cascoded differential amplifiers (204,205,206 and 207), each pair of which is connected to generate two phase quadrature signals between respective outputs of the pair of transistors (201,202) and two output terminals (218, 219, 220 and 221) of active quadrature signals:
- and
- two pairs of low pass filters and high pass filters (231, 232, . . . ), wherein each pair of the low pass filter and high pass filter is connected between output terminals (218, 219, 220 and 221) of the active quadrature signals and supply voltage (Vdd), the low-pass filter including a resistor and a capacitor, the high-pass filter including a resistor and an inductor.
Dependencies are inferred from the claim text.