# A Reconfigurable Radio-Frequency Converter IC in 0.18 \(\upmu\)m CMOS
## 5 Conclusions  
This work presents the design and validation of a reconfigurable RF converter for DVB-T television applications. The system is designed to operate in a triple-play architecture over GPON using a carrier at 1550 nm (third lambda) and spectrum inversion.  
By the joint integration of two pairs of frequency synthesizer and mixer, the RF converter in this work takes the DVB-T input, a WDM signal with spectral inversion, formed by 8 MHz channels in the range from 47 MHz to 1000 MHz, and up-converts its frequency to the band-pass of a highly selective SAW filter centered at 1.3 GHz. The resulting signal is subsequently down-converted by the other frequency synthesizer and mixer so that it can be directly input to a television set.  
The mixers designed are two double-balanced structures based on the Gilbert cell, with their input RF signals input through the transistor sources for better impedance matching and improved linearity, which can be programmed to operate in a low-power mode or a high-linearity mode. The frequency synthesizer uses two \(LC\)-tank VCOs inside an integer-N PLL and a 20 MHz TCXO reference to generate the desired local oscillator signal in a frequency range from 1.35 GHz to 2.7 GHz. The system is fed with regulated supplies compensated in temperature and programmed by an I\({}^{2}\)C interface operating on five 16-bit registers.  
All in all, the combination of third lambda transmission and spectrum inversion allows operators to alleviate the saturation of the bandwidth in GPONs by broadcasting all traditional television channels using the additional down-link at 1550 nm, and leaving for IP transmission over the conventional up- and down-links at 1310 nm and 1490 nm for premium content requiring added login security. Finally, another advantage of this solution is that the resulting demodulated signal can  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Oscillator** & \(VCO_{1}\) & \(VCO_{2}\) & \\ \hline Frequency Range & 1.33–2.08 & 2.06–2.73 & GHz \\ Tuning Gain & 25 & 25 & MHz V\({}^{-1}\) \\ Phase Noise & \(-122\) & \(-117\) & dBkHz\({}^{-1}\) \\ Power & 25 & 25 & mW \\ Area & \(800\times 350\) & \(900\times 450\) & \(\upmu\)m\({}^{2}\) \\ \hline
**Mixer** & _Low Power_ & _High Linearity_ & \\ \hline RF-IF Frequency & & 30–2500 & MHz \\ Up-Conversion Gain & & 0.3 & dB \\ Down-Conversion Gain & & 2.2 & dB \\ Noise Figure & 17.4 & & 19.5 & dB \\ IIP\({}_{3}\) & +12 & & 15.5 & dBm \\ P\({}_{in}\) 1 dB & +2.3 & & 4.5 & dBm \\ Power & 15 & & 39 & mW \\ \hline \hline \end{tabular}
\end{table}
Table 1: Performance summary of the fabricated prototypes (RFID-II).  
Figure 9: Measured response of the mixers: (**a**) noise figure and gain as a function of the RF input frequency, (**b**) noise figure and gain as a function of temperature and (**c**) 1 dB compression point and third-order intercept point as a function of the RF input frequency.  
be fed to any television set without the need for a decoder, facilitating the implementation and use of this service.  
[PERSON] carried out the main research and wrote the paper. [PERSON] and [PERSON] collaborated in the design and characterization of the prototypes. This work was carried out under the supervision of [PERSON]. All authors were involved in the discussion of the results and the modifications of the paper.  
This research was partially funded by MICINN-FEDER under grants TEC2014-52840-R and TEC2017-85867-R.  
The authors would like Telnet, R.I. for the realization of the PCBs for experimental testing. Also, the authors would also like to acknowledge the staff of the Group of Electronic Design (GDE), Universidad de Zaragoza, Spain, for their assistance in the layout of the auxiliary circuitry.  
The authors declare no conflict of interest.