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Circuit for reconstructing an analog signal from a digital signal and transmission system, particularly for wcdma cellular telephony, including such circuit

A technology of analog signal and digital signal, applied in the field of broadband transmission system and transmission system, it can solve the problems of high current consumption and large silicon area.

Inactive Publication Date: 2011-11-23
STMICROELECTRONICS SRL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

All of the above has been done, therefore, the silicon area required for integration is quite large and the current consumption is still relatively high (tens of mA)

Method used

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  • Circuit for reconstructing an analog signal from a digital signal and transmission system, particularly for wcdma cellular telephony, including such circuit
  • Circuit for reconstructing an analog signal from a digital signal and transmission system, particularly for wcdma cellular telephony, including such circuit
  • Circuit for reconstructing an analog signal from a digital signal and transmission system, particularly for wcdma cellular telephony, including such circuit

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Embodiment Construction

[0016] Figure 5 It is shown that the included can be advantageously used respectively for use in mobile phones or more generally in applications such as figure 1 Circuit arrangement or reconstruction circuit of the digital-to-analog converter (DAC) and the filter (LOW-PASS) of the module DAC and the module LOW-PASS in the transmission front end in the mobile communication device of . Advantageously, the DAC is of the current-steering type (current-steering DAC), and the low-pass filter is an active filter, preferably of the differential Butterworth type in the example realized as a Rauch filter. In a particularly preferred embodiment, the filter is galvanically coupled directly to the DAC output, and is preferably, without limitation, a second order filter. In alternative embodiments, the filter is, for example, a first order or third order filter.

[0017] The DAC shown in the attached figure comprises no more than 4 bits for the simplification of the description; however,...

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Abstract

There is described a circuit for reconstructing an analog signal from a digital signal and wide-band transmission system, particularly for employment in cellular telephony systems, or more in general in mobile communication systems, that adopt the WCDMA standard. The circuit comprises: a digital to analog converter (DAC) suitable for receiving said digital signal and converting it into signal in analog format; a low pass-filter (LOW-PASS) connected at the output of said converter for receiving said signal in analog format and providing as output said reconstructed analog signal. Advantageously, the low pass filter (LOW-PASS) is an active filter continuous in time and current coupled to the output of the digital-analog converter (DAC) and the digital-analog converter (DAC) is a converter of the current-steering type functioning at sampling frequency greater than the Nyquist frequency of said analog signal to be reconstructed.

Description

technical field [0001] The present invention relates to the technical field of broadband transmission systems, in particular to their use in mobile communication systems employing the WCDMA standard, and in particular to circuits for reconstructing analog signals from digital signals and transmission systems comprising such circuits. Background technique [0002] Digital cellular telephones, or more generally, mobile communication digital devices, use quadrature modulation (I / Q) to vary the frequency or phase of a radio frequency carrier. Two signals, typically denoted I and Q, are required for this type of modulation, which modulate the carrier in phase and in quadrature (90 degrees out of phase), respectively. The two modulated carriers are summed with each other to obtain the composite signal to be transmitted. figure 1 A block diagram showing the transmission portion of a cellular phone (in Figure 6 are represented schematically). The modulator MOD receives as input ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B1/707H03M1/74
CPCH04B1/707
Inventor 杰尔马诺·尼科利尼皮耶兰杰罗·孔法洛涅里利卡多·马蒂尼奥内
Owner STMICROELECTRONICS SRL