A promising ultra-wideband radio technology being widely considered for low data rate applications is the transmitted reference ultra-wideband scheme. One of its important applications is found in the area of radio frequency identification that requires low cost, low power consumption and low complexity radio frequency tags for its operation. However, although the standard transmitted reference scheme produces low complexity tag receiver structure, it is not energy efficient and the error performance is not as good as a full rake receiver. In this work, two transmitted reference scheme, which are known as transmitted-reference 4 pulse interval amplitude modulation (TR 4PIAM) and its enhanced version TR hybrid 4PIAM, are being studied analytically and verified through simulations. The two schemes improves the energy efficiency of the transmitter while maintains a low complexity as compared to a full rake receiver. This work should be useful to anyone else who may want to understand the analytical performance of the variants of transmitted reference scheme in the application of radio frequency identification.