ADC testing using digital stimuli

Abstract

In semiconductor products, a system-on-chip (SoC) is a very popular type of IC. It Chapter 1 Introduction 6 integrates an electronic system on one single chip. It is widely used in communication systems, video and audio applications. A typical SoC design contains multiple individual building blocks or cores, which can be processors, memories, input and output interface (IO), analogue, mixed-signal and radio-frequency (RF) circuits, etc [ITR09]. However, the test cost of the individual parts is very different from each other. The test cost per mm 2 of mixed-signal blocks is at least 10 times higher than digital blocks [Ara10]. Due to the recent innovative test technology, the test cost of digital blocks has been dramatically reduced. However, the analogue and mixed-signal test technology develop relatively slow resulting in a growing contribution of mixed-signal test cost to the overall SoC test cost. In a SoC, the analogue, mixed-signal and RF dominate the production test cost, which can be up to 70% of the overall test costs [Ste11]. It is obvious that industry requires the innovations of mixed-signal test technology to test them efficiently. 1.2 Mixed-signal testing Mixed-signal circuits are widely used in our daily life nowadays [Vri10]. As the technology is developing, people design mixed-signal circuits with increased performance. Apart from the design, how to test mixed-signal circuits efficiently and accurately is also very important as well. It will directly determine whether the devices can be delivered to the customers in time with a good quality. However, this is not an easy task. In this section, the basic knowledge of mixed-signal testing is introduced and its bottlenecks are also explained. 1.2.1 Mixed-signal testing in a production environment Mixed-signal circuits can be defined as circuits including both analogue and digital components [Bur00]. Typical mixed-signal circuits are analogue-to-digital converters (ADC) and digital-to-analogue converters (DAC); they are considered as the interfaces between the analogue and the digital world. Another typical mixed-signal circuit is the phase-locked loop (PLL), which is used to generate high-frequency clock signals or clock signals with a certain phase shift from the reference clock [Sai11]. An RF front-end is also a very widely used mixed-signal circuit as they are crucial part of the communication systems. It is used to convert the received RF signal to the desired original signal to modulate the original signal to an RF signal for transmission. Mixed-signal circuits are usually integrated into all kinds of applications, like mobile phones, motor controllers, audio and video products.