Time filter

Source Type

Basar M.R.,University Malaysia Perlis | Malek F.,University Malaysia Perlis | Juni K.M.,Politeknik Tuanku Syed Sirajud din PTSS | Idris M.S.,Politeknik Tuanku Syed Sirajud din PTSS | Saleh M.I.M.,Politeknik Tuanku Syed Sirajud din PTSS
Progress In Electromagnetics Research B | Year: 2013

Just over a decade ago, wireless capsule endoscopy (WCE) was introduced as a novel alternative to conventional wire or probe endoscopy to examine disorders of the human gastrointestinal (GI) tract. Yet, the persistent inability of transmitting high-quality images due to limited data rate of the telemetry system continues to be an issue of major concern. Thus, high-data-rate telemetry systems are essential due to the widespread use of the WCE technique. In this paper, we present such a telemetry system that includes a highly-simplified receiver for the use in WCE. Unlike the conventional architecture of a radio frequency (RF) receiver, the architecture of the new receiver allows the direct conversion of analog RF signals to digital signals, eliminating the need for any frequency conversion in the analog domain. Our receiver system consists of sub-blocks, a low-noise amplifier (LNA), a logarithmic amplifier (LA), a power detector (PD), and a comparator. The common-source cascode LNA was designed with its frequency spectrum centralized at 450 MHz, which was determined by electromagnetic (EM) simulation of the path loss in the GI tract of the human body. To ensure that the higher data rate, i.e., 100 Mbps, could be attained, the LNA was designed for a system bandwidth of 100 MHz, i.e., 400-500 MHz. The LNA and the three cascading blocks in combination have total gain of 80 dB to compensate for the losses in the weak signals that are received. The LNA and the LA, including the PD and the comparator, require 17-mA and 337-μA currents, respectively, from a 1.5-V, DC source. Source

Basar M.R.,University Malaysia Perlis | Malek F.,University Malaysia Perlis | Saleh M.I.M.,Politeknik Tuanku Syed Sirajud din PTSS | Idris M.S.,Politeknik Tuanku Syed Sirajud din PTSS | And 4 more authors.
Progress in Electromagnetics Research | Year: 2013

Wireless capsule endoscopy (WCE) was developed as a painless diagnostic tool for endoscopic examination of the gastrointestinal (GI) tract, but, to date, the low operating power of the capsule and the high data rate of the RF telemetry system are still key concerns. Innovative, novel solutions must be developed to address these concerns before WCE can be used extensively in clinical applications. In this paper, we propose a novel RF transmitter for WCE applications that only requires 1.5V to transmit the required data as opposed to using a DC power supply. Our proposed, direct-conversion transmitter system consists of a current reuse oscillator, an envelope filter, and an L-section matching network. The oscillator is powered by the transmitting data which keep the oscillator in turned on and off for the transmitting 1 and 0 bit respectively and results in the on-off keying (OOK) of the modulated signal at the output of the oscillator. The rate of data transmission at the modulated signal is limited by the transient period of the oscillator start-up. When the start-up time of the oscillator is optimized, an OOK modulation rate of 100 Mb/s can be attained. In order to eliminate the oscillator decay noise, we used an envelope filter connected in series with the oscillator to filter out the decay part of the oscillation. Finally, the output impedance of the envelope filter is matched to the 50-Ω antenna with an L-section, low-pass, matching network to ensure maximum power transmission. The entire transmitter system was simulated in a 0.18- μm Complementary metal-oxide-semiconductor (CMOS) process. Source

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