A GSM/EDGE/WCDMA modulator with on-chip D/A converter for base stations

Vankka, Jouko; Ketola, J.; Sommarek, J.; Väänänen, Olli; Kosunen, Marko; Halonen, K.

doi:10.1109/tcsii.2002.807268

Cited by 16 publications

(9 citation statements)

References 15 publications

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“…The screen shots for spectrum and EVM measurements are shown in Figure 12. In the 20 MHz passband, the measured ACLR is 45 dB, which can meet the requirement for WCDMA [15]. The noise shaping effects can clearly be seen from the spectrum plot where the noise rises outside the RF signal bandwidth.…”

Section: Implementation Resultsmentioning

confidence: 56%

“…The double lines connecting different blocks indicate that there are two identical datapaths for both inphase path and quadrature path (I and Q). In a traditional modulator, a quadrature direct digital frequency synthesizer (QDDFS) will be used to modulate the signal to intermediate frequency (IF), and then the digital output is converted to analog signal using DAC [1,15]. In the all-digital transmitter presented in this paper, an RFPWM will be used to directly synthesize RF signals in digital domain.…”

Section: Universal Qam Modulatormentioning

confidence: 99%

“…A different control approach is to use the MSB of the NCO register as the reference clock for the delay line as shown in Figure 6. This reference clock is further divided down to provide sample rate clocks to the different interpolation filters inside the multi-stage upsampling filters [1,15]. The novelty of our implementation only requires one system clock for all the filter stages.…”

Section: Sample Rate Convertermentioning

confidence: 99%

“…The first category consists of architectural study and implementation of digital modulators and transmitters. All digital modulators implemented on ASIC were presented by Cho and Samueli [1] and Vankka et al [15]. SDR based architecture using FPGAs is presented by Lee et al [9] and Sheen et al [13] for CDMA2000 and WCDMA, respectively.…”

Section: Related Workmentioning

confidence: 99%

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An FPGA Based All-Digital Transmitter with Radio Frequency Output for Software Defined Radio

Ye¹,

Grosspietsch²,

Memik

2007

2007 Design, Automation &Amp; Test in Europe Conference &Amp; Exhibition

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Section: Implementation Resultsmentioning

confidence: 56%

Section: Universal Qam Modulatormentioning

confidence: 99%

Section: Sample Rate Convertermentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

See 2 more Smart Citations

An FPGA Based All-Digital Transmitter with Radio Frequency Output for Software Defined Radio

Ye¹,

Grosspietsch²,

Memik

2007

2007 Design, Automation &Amp; Test in Europe Conference &Amp; Exhibition

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“…Another advantage of using digital-IF mixing is to avoid the clock feedthrough which is located at the RF center frequency. Digital-IF mixing to f s /4 is a digital multiplier-free quadrature modulation that utilizes a multiplexer to implement multiplication by 1, -1 and 0 [41][42][43][44]. This technique is very hardware and power efficient.…”

Section: Alleviate the Image Spur Problem With Digital If Mixingmentioning

confidence: 99%

On High-Speed Digital-to-Analog Converters and Semi-Digital FIR Filters

Sadeghifar¹

2015

Linköping Studies in Science and Technology. Thesis

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High-speed and high-resolution digital-to-analog converters (DACs) are vital components in all telecommunication systems. Radio-frequency digital-to-analog converter (RFDAC) provides high-speed and high-resolution conversion from digital domain to an analog signal. RFDACs can be employed in direct-conversion radio transmitter architectures. The idea of RFDAC is to utilize an oscillatorypulse-amplitude modulation instead of the conventional zero-order hold pulse amplitude modulation, which results in DAC output spectrum to have highenergy high-frequency lobe, other than the Nyquist main lobe. The frequency of the oscillatory pulse can be chosen, with respect to the sample frequency, such that the aliasing images of the signal at integer multiples of the sample frequency are landed in the high-energy high-frequency lobes of the DAC frequency response. Therefore the high-frequency images of the signal can be used as the output of the DAC, i.e., no need to the mixing stage for frequency upconversion after the DAC in the radio transmitter. The mixing stage however is not eliminated but it is rather moved into the DAC elements and therefore the local oscillator (LO) signal with high frequency should be delivered to each individual DAC element.In direct-conversion architecture of IQ modulators which utilize the RFDAC technique, however, there is a problem of finite image rejection. The origin of this problem is the different polarity of the spectral response of the oscillatorypulse-amplitude modulation in I and Q branches. The conditions where this problem can be alleviated in IQ modulator employing RFDACs is also discussed in this work.Σ∆ modulators are used preceding the DAC in the transmitter chain to reduce the digital signal's number of bits, still maintain the same resolution. By utilizing the Σ∆ modulator now the total number of DAC elements has decreased and therefore the delivery of the high-frequency LO signal to each DAC element is practical. One of the costs of employing Σ∆ modulator, however, is a higher quantization noise power at the output of the DAC. The quantization noise is ideally spectrally shaped to out-of-band frequencies by the Σ∆ modulator. The shaped noise which usually has comparatively high power must be filtered out to fulfill the radio transmission spectral mask requirement.Semi-digital FIR filter can be used in the context of digital-to-analog conversion, cascaded with Σ∆ modulator to filter the out-of-band noise by the modulator. In the same time it converts the signal from digital domain to an analog quantity. In general case, we can have a multi-bit, semi-digital FIR filter where each tap of the filter is realized with a sub-DAC of M bits. The delay elements are also realized with M-bit shift registers. If the output of the modulator is given by a single bit, the semi-digital FIR filter taps are simply controlled by a single switch assuming a current-steering architecture DAC. One of the major advantages is that the static linearity of the DAC is optimum. Since there are only t...

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16. A GSM/EDGE/WCDMA Modulator with On-chip D/A Converter for Base Stations

Digital Synthesizers and Transmitters for Software Radio

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A GSM/EDGE/WCDMA modulator with on-chip D/A converter for base stations

Cited by 16 publications

References 15 publications

An FPGA Based All-Digital Transmitter with Radio Frequency Output for Software Defined Radio

An FPGA Based All-Digital Transmitter with Radio Frequency Output for Software Defined Radio

On High-Speed Digital-to-Analog Converters and Semi-Digital FIR Filters

16. A GSM/EDGE/WCDMA Modulator with On-chip D/A Converter for Base Stations

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